This is about our collective future. It is about the kind of world we want our children to grow up in.

It is about - and exclusively about - whether the world should tolerate the repeated use of chemical weapons and the human suffering they cause.

The problem with such weapons is not just that their effect is hideous. Anyone looking at the pictures from Eastern Ghouta can see the kind of suffering involved: the foaming at the mouth, the floppy bodies of children, and the particular terror those weapons deliberately inspire.